If the recent heat and wildfires have taught us anything, it's the need to have cooler, cleaner air. Want to upgrade your window AC unit? Maybe you're thinking about buying a new air purifier. Tim Heffernan and Thom Dunn, writers at Wirecutter, discuss their favorite purifiers and HVAC (Heating, Ventilation, and Air Conditioning) products. Plus we take your calls.

• A Post-show note for listeners from Tim Heffernan: "[Air purifier filters] capture big dust and pet hair and can clog up quickly, reducing its effectiveness. For anyone here who owns an air purifier.. clean yours once a month!"